Fabrication of blade blanks



Oct. 9, 1962 D. J. CLARKE 3,957,393

FABRICATION OF BLADE BLANKS Filed June 3 1957 3 Sheets-Sheet 1 DANIEL J.CLARKE MMMW ATTORNEYS Oct. 9, 1962 D. J. CLARKE FABRICATION OF BLADEBLANKS 3 Sheets$heet 3 Filed June 5. 1957 INVENTOR.

DANIEL J. CLARKE ATTORNEYS 3,057,393 Patented Oct. 9, 1962 Free3,057,393 FABRICATION F BLADE BLANKS Daniel J. Clarke, Bay City, Michassignor to The Stalker Corporation, a corporation of Michigan FiledJune 3, 1957, Ser. No. 663,251 6 Claims. (Cl. 153-33) This inventionrelates to an apparatus and method for forming blades for compressors,turbines and the like, and more particularly to an apparatus and methodfor folding preformed sheet metal blade blanks about the leading edge ofthe nose portion to place the trailing edges of the blank into closeproximity for joining.

Another object of this invention is to provide a method and apparatusfor folding preformed sheet metal blade blanks about a supportingmandrel through the application of comparatively large side forcesexerted against the outer portion of the supporting mandrel whichprevent excessive mandrel wear While bringing the trailing edges intoadjoining relationship.

A primary object of this invention is to to provide an apparatus forfolding a preformed blade blank about its leading edge while preservingits precisely formed contours.

Another object of this invention is to provide a method and apparatusfor reforming the outer, supporting edge of such a mandrel.

Other objects and advantages of this invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

In the drawings:

FIG. 1 is a perspective view showing an apparatus ac cording to thepresent invention with a preformed blade blank supported on the mandrel;

FIG. 2 is a perspective view of a shaping bar secured in position on ashaping arm;

FIG. 3 is an end elevation of the shaping press in operation with thesupporting mandrel and preformed blade blank in section;

FIG. 4 is a side elevation of the apparatus of FIG. 3 on a slightlyreduced scale;

FIGS. 5-7 are fragmentary sections showing the cooperation between theshaping bars and the supporting mandrel as a blank blade is folded;

FIG. 8 is a cross section through a folded blank showing the trailingedges in close proximity for joining; and

FIG. 9 is a sectional fragmentary perspective showing a completed bladeshape.

Referring to the drawings which illustrate a preferred embodiment of theinvention, a first or lower mounting plate 10 has a pair of supportingstandards 11 extending from two corners thereof and a pair of elongatedmandrel supports 12 which are attached to mounting plate 10 by nuts 13and bolts 14. A supporting mandrel 15 is removably attached to mountingplate 10 and supports 12 by means of set screws 16 which extend throughthe supports 12 into the base portion of the mandrel.

The supporting portion 17 of mandrel 15 is constructed into a shapecorresponding substantially to the cross sectional shape of a completedcompressor or turbine blade in order that the precisely formed contoursof the blank 18 can be preserved during the folding operation. The blank18 includes a leading edge 19, a nose portion 20, which constitutes thatportion of the blank immediately adjacent each side of leading edge 19,and trailing edges 21. Trailing edges 21, best shown in FIG. 8, arelocated at the point where the folded sides make contact at the dishedportion of the sides just ahead of the excess portions 22, the portions22 being removed in subsequent operations. An abutment 23 is formed ateach end of the shaping mandrel to provide for accurately positioning 'ablade blank 18 on the mandrel prior to the folding operation. The uppersurfaces 24 of the abutments 23 control the downward travel of theshaping bars as shown in sequence in FIGS. 5-7.

A second or upper mounting plate 25 is attached to standards 11 by meansof apertured ears 26, which extend outwardly from two corners of themounting plate 25, to provide a plate for movement in opposition to thefirst plate 10. Holding means 27 is attached to that surface of mountingplate 25 which faces the lower mounting plate so that shaping arms 30can be mounted for cooperation with the mandrel 15. The holding means 27includes a pair of generally parallel arms 31 having inwardly directedhinge plates 32 which are spaced to cooperate with extensions 35 on theshaping arms 30 so that hinge pins 36 can be placed within the axiallyaligned holes 37. Holes 37 extend through hinge plates 32 and extensions35 to provide for pivotal attachment of the arms 30 to holding means 27.

The inner end of each shaping arm 30 has a cut-out portion 40 forreceiving an elongated shaping bar 41, the shaping bar being removablysecured to its shaping arm 30 by means of screws 42 and retaining plates43 which are held in position by screws 44. The adjoining inner ends ofshaping arms 30 are close enough together that the upper corners willalmost touch when the arms are resting in their lowermost position, asshown in FIG. 5 of the drawings. It should be noted that retaining bolts45, having washers 46, extend through openings 47 in arms 30 forthreaded engagement with holding means 27 to provide a positive limit onthe downward travel of the arms 30.

It is normally preferred that upward movement of arms 30 present someresistance to the mandrels so that the blade blank 18 will be urgedtightly against the mandrel. This is accomplished by a plurality of coilsprings 50 which bias the spacing arms 30 toward their lowermostposition so that the shaping bars 41 will form a generally V-shapednotch 51 for receiving the upper edge of mandrel 15 together with theblade blank.

In the operation of the shaping apparatus the upper mounting plate 25and lower mounting plate 10 are placed in a press for relative movementtoward each other and preformed sheet metal blade blank 18 is positionedon mandrel 15 so that its nose portion 20 and leading edge 19 will besupported by the upper edge of the mandrel. FIGS. 5 through 7 indicatethe manner in which the blade blank is subjected to a folding forceresulting from the toggle-like action of the opposed, cooperatingshaping hars 41 on shaping arms 30. As the upper shaping means islowered to make contact with mandrel 15, or vice versa, the nose portionof the blade and the supporting mandrel move into notch 51, contactbeing initially made with shaping bars 41 immediately adjacent each sideof leading edge 19 of the nose portion 20. As the movement is continuedthe shaping arms begin to swing upwardly and exert substantial lateralor side forces against the nose portion of blade blank 15 andconsequently bend the blank about leading edge 19.

The vertical force, i.e. that which acts against the blank in the samegeneral direction as a blade chord, is comparatively light since thebars 41 continually retreat against the biasing force of springs 50 asthe blade is forced further into notch 51. Since the notch 51 closesduring the pivotal movement of arms 30 the blade is subjected totransversely acting forces beginning adjacent each side of the leadingedge 19 and continuing therefrom toward the trailing edges 21 to foldthe blade blank about its leading edge. Since the cross sectionalsectional area of a completed blade the blade can be folded far enoughto insure that it will achieve the proper shape without the necessity offurther forming operations.

The present invention is of particular utility in those cases where thenose radii of the complete blade is extremely small, for example on theorder of the thickness of the blade wall. The use of high verticalforces in folding the blade blanks about the mandrel would cause failureof the mandrel after a relatively few folding operations. However wherethe folding operation is largely accomplished by large side ortransversely directed forces close to the leading edge of the blank andthere is limited pressing or dragging by friction of the blankvertically downward against this edge, the mandrel will withstandthousands of folding operations. This is particularly true in thisinvention since the large side forces tend to rework and reform themandrel while it is within the nose of the blade blank eliminatingdistortions of the mandrels edge which may have occurred accidentally orthrough the operation with an incorrect blade blank.

The edge of the mandrel 15 is also protected against large verticalforces by the retaining plates 43 which strike abutments 24 at each endof the mandrel when the mandrel and the shaping arms 30 are being movedrelatively together. Thus the upward pivotal movement of the shapingbars is completed by reason of the plates 43 coming into contact withabutments 24. Plates 43 may be of varied thicknesses to achievedifferent degrees of vertical and side forces, the amount of each of theforces used depending upon the shape and the size of mandrel present.With proper selection of plate thicknesses the vertical forces can be ofslight magnitude while preserving relatively greater side forces toachieve proper folding of a blade blank about the mandrel. It will thusbe clear that the main folding action of the shaping arms results fromthe contact of the plates 43 with the abutments 24 and not from theopposition of the edge of the mandrel.

The present apparatus is also useful in reforming the upper edges of amandrel which have become deformed from long use. By exerting the largetransversely directed forces against the nose portion of the mandrel, itcan be shaped by the roller-like action of the toggle construction toreform it into proper configuration. The operation is analogous to thatdescribed in connection with the folding of the blade blanks.

While the form of apparatus and method herein described constitutespreferred embodiments of the invention, it is to be understood that thisinvention is not limited to these precise forms of apparatus and methodand that changes may be made therein without departing from the scope ofthe invention which is defined in the appended claims.

What is claimed is:

1. An apparatus for folding an open, preformed contoured blade blankabout the leading edge of its nose portion to bring the trailing edgesinto close proximity for joining while preserving the preformed contoursover the major portion of both blade surfaces, said apparatus comprisinga fixed mandrel conforming to the configuration of and receiving thereonthe nose portion of said blade blank to provide support therefore, bladenose shaping means mounted in opposition to said blade blank, and meansfor applying force directly to said shaping means to exert "atransversely acting force against the nose portion only of said bladeblank beginning adjacent each side of the leading edge and continuingtherefrom over the forward portion of said blank to fold said bladeblank about its leading edge leaving the major portions of said blankrearward of said forward portion with said preformed contours therein.

2. An apparatus for folding an open, preformed contoured blade blankabout the leading edge of its nose portion to bring the trailing edgesinto close proximity for joining, said apparatus comprising a firstmounting plate, a mandrel having a shape conforming substantially to theshape of a completed blade up to the trailing edge thereof secured tosaid mounting plate and providing support for said blade blank, a secondmounting plate supported in opposition to said first mounting plate,shaping means attached to said second mounting plate, said shaping meansincluding a pair of pivotally mounted cooperating shaping bars arrangedfor contact with the nose portion only of said blank adjacent each sideof the leading edge thereof, and means responsive to the relativemovement of said plates for operating said shaping means independentlyof the engagement of said nose portion therewith to limit the chordwiseforce on said mandrel and to exert transversely acting forces on saidblade blank which fold said blank about its leading edge leaving themajor portion of said blank with said preformed contours therein.

3. Apparatus for working an open, preformed contoured blade blank toform a folded blade with nose radii in the order of thickness of theblade wall and to bring the trailing edges into close proximity forjoining, comprising a press including a first mounting plate thereon, amandrel having a relatively sharp leading edge secured to said firstmounting plate providing support for said blade blank, a second mountingplate supported on said press for relative movement with said firstplate, a pair of opposite shaping bars pivotally attached to said secondmounting plate for closing movement in pressure contact with the noseportion of said blank adjacent each side of the leading edge forexerting transverse forces on said blank to fold said blank about theleading edge thereof, and an abutment forming an integral extension ofsaid mandrel engageable with said bars to complete said closing movementthereof upon relative movement of said plates, said bars and abutmentbeing pro portioned to limit said relative movement for protecting saidmandrel against excess pressures normal to the leading edge thereof.

4. Apparatus for working an open, preformed contoured blade blank toform a folded blade with nose radii in the order of thickness of theblade wall and to bring the trailing edges into close proximity forjoining, comprising a press including a first mounting plate thereon, amandrel ahving a relatively sharp leading edge and having a crosssectional area less than the internal cross sectional area of suchcompleted blade, said mandrel being secured to said first mounting plateproviding support for said blade blank, 2. second mounting platesupported on said press for relative movement with said first plate, apair of opposite shaping arms pivotally attached to said second plate, ashaping bar secured to each of said shaping arms for movement with saidarms to a closed position in pressure contact with the nose portion ofsaid blank adjacent each side of the leading edge for exertingtransverse forces on said blank to fold said blank about the leadingedge thereof into conformity with said mandrel leading edge, and a pairof abutments forming integral extension of said mandrel positioned ateach end thereof engageable with said arms to complete closing movementthereof upon relative movement of said plates and said abutments andarms being proportioned to limit said relative movement for protectingsaid mandrel against excess pressures normal to the leading edgethereof.

5. Apparatus for working an open, preformed contoured blade blank toform a folded blade with nose radii in the order of thickness. of theblade wall and to bring the trailing edges into close proximity forjoining, comprising a press including a first mounting plate thereon, "amandrel having a leading edge conforming substantially to the internalconfiguration of the leading edge of a completed blade and having across sectional area less than the internal cross sectional area of suchcompleted blade, said mandrel being secured to said first mounting plateproviding support for said blade blank, a second mounting platesupported on said press for relative movement with said first plate,holding means having hinge plates extending from a surface thereofattached to said second mounting plate, a pair of opposite shaping armsattached to the hinge plates of said holding means, a shaping barsecured to each of said shaping arms for movement with said arms to aclosed position in pressure contact with the nose portion of said blankadjacent each side of the leading edge for exerting transverse forces onsaid blank to fold said blank about the leading edge thereof intoconformity with said mandrel leading edge, plates removably cartried oneach end of said arms adjacent said bars, and a pair of abutments formedon extended portions of said mandrel engageable with said arms at saidplates to complete closing movement thereof upon relative movement ofsaid plates, said abutments and plates being proportioned to limit saidrelative movement for protecting said mandrel against excess pressuresnormal to the leading edge thereof.

6. The method of completing the folding of an open, partially foldedpreformed contoured sheet metal blade blank about the leading edge ofits nose portion to form the completed blade shape characterized by anose radii in the order of the thickness of the blade Wall compris ing,supporting the partially folded blade blank on a mandrel having asupporting leading edge surface conforming to the desired internalconfiguration of the completed blade nose portion, exerting a verticallydirected force on the nose portion only of the blade blank to urge thenose portion into firm engagement with the mandrel, and simultaneouslyapplying transversely directed forces directly to the blade blank whilelimiting said vertically directed force to fold the blade about itsleading edge in conformity With said mandrel and bring the trailingedges into close proximity for joining, said transversely acting forcesbeing progressively applied to said nose portion beginning adjacent eachside of the leading edge and moving therefrom over the forward portiononly of said blank leaving the major chordwise extent thereof unworkedand with its original contours therein.

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